President Donald Trump says he's open to talking with the North Korean leader he's called "Rocket Man" and is hoping some good can come from upcoming talks between the Koreas.

Trump tells reporters at Camp David that he "always believes in talking."

North and South Korea have agreed to discuss cooperation on the upcoming Olympics in South Korea, as well as other issues, in rare talks set to begin Tuesday.

Trump calls that "a big start." He says if "something can come out of those talks that would be a great thing for all of humanity."

He says North Korea's Kim Jong Un — who's threatened the U.S. with a nuclear attack — "knows I'm not messing around, not even a little bit, not even 1 percent."